Science vs Conspiracy: Collective Narratives in the Age of Misinformation

The large availability of user provided contents on online social media facilitates people aggregation around shared beliefs, interests, worldviews and narratives. In spite of the enthusiastic rhetoric about the so called collective intelligence unsubstantiated rumors and conspiracy theories—e.g., chemtrails, reptilians or the Illuminati—are pervasive in online social networks (OSN). In this work we study, on a sample of 1.2 million of individuals, how information related to very distinct narratives—i.e. main stream scientific and conspiracy news—are consumed and shape communities on Facebook. Our results show that polarized communities emerge around distinct types of contents and usual consumers of conspiracy news result to be more focused and self-contained on their specific contents. To test potential biases induced by the continued exposure to unsubstantiated rumors on users’ content selection, we conclude our analysis measuring how users respond to 4,709 troll information—i.e. parodistic and sarcastic imitation of conspiracy theories. We find that 77.92% of likes and 80.86% of comments are from users usually interacting with conspiracy stories.     

MicroDSC study of Staphylococcus epidermidis growth

Background  

A microcalorimetric study was carried out using a Staphylococcus epidermidis population to determine the reproducibility of bacterial growth and the variability of the results within certain experimental parameters (temperature, bacterial concentration, sample thermal history). Reproducibility tests were performed as series of experiments within the same conditions using either freshly prepared populations or samples kept in cold storage. In both cases, the samples were obtained by serial dilution from a concentrated TSB bacterial inoculum incubated overnight.     

In vitro assessment of the antimicrobial activity of new N-acyl-thiourea derivatives

The qualitative screening of the susceptibility spectra of different microbial strains to the newly synthesized substances complexes was performed by adapted disk diffusion techniques, while the quantitative assay of the minimal inhibitory concentration (M.I.C., microg/cm3) value was based on liquid medium serial microdilutions. The compounds were solubilized in dimethylsulfoxide (DMSO). The in vitro biological screening effects were tested against a microbial inoculum of approximately 1.5 x 10(8) UFC/cm3, corresponding to 0.5 McFarland standard density, obtained from Gram positive (Staphylococcus aureus, Bacillus subtilis), Gram negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) and fungal strains (Candida albicans). In order to investigate the influence of the subinhibitory concentration of the tested substances on the expression of different virulence features, the strains were incubated overnight in the presence of the newly synthesized thiourea derivatives (vol:vol) and different virulence features were investigated, i.e: adherence capacity to the cellular substrate represented by HeLa cells and to inert substrata quantified by slime test and soluble enzymatic virulence factors (haemolysins and other pore-forming toxins, proteases activity, DN-ase and siderophores production). The cytotoxicity was assessed microscopically, by observing the effect of the tested compounds on the cellular substratum integrity.     

Soluble Sema4D cleaved from osteoclast precursors by TACE suppresses osteoblastogenesis

Bone remodelling is mediated by orchestrated communication between osteoclasts and osteoblasts which, in part, is regulated by coupling and anti-coupling factors. Amongst formally known anti-coupling factors, Semaphorin 4D (Sema4D), produced by osteoclasts, plays a key role in downmodulating osteoblastogenesis. Sema4D is produced in both membrane-bound and soluble forms; however, the mechanism responsible for producing sSema4D from osteoclasts is unknown. Sema4D, TACE and MT1-MMP are all expressed on the surface of RANKL-primed osteoclast precursors. However, only Sema4D and TACE were colocalized, not Sema4D and MT1-MMP. When TACE and MT1-MMP were either chemically inhibited or suppressed by siRNA, TACE was found to be more engaged in shedding Sema4D. Anti-TACE-mAb inhibited sSema4D release from osteoclast precursors by ~90%. Supernatant collected from osteoclast precursors (OC-sup) suppressed osteoblastogenesis from MC3T3-E1 cells, as measured by alkaline phosphatase activity, but OC-sup harvested from the osteoclast precursors treated with anti-TACE-mAb restored osteoblastogenesis activity in a manner that compensates for diminished sSema4D. Finally, systemic administration of anti-TACE-mAb downregulated the generation of sSema4D in the mouse model of critical-sized bone defect, whereas local injection of recombinant sSema4D to anti-TACE-mAb-treated defect upregulated local osteoblastogenesis. Therefore, a novel pathway is proposed whereby TACE-mediated shedding of Sema4D expressed on the osteoclast precursors generates functionally active sSema4D to suppress osteoblastogenesis.     

Molecular architecture of annelid nerve cord supports common origin of nervous system centralization in bilateria

To elucidate the evolutionary origin of nervous system centralization, we investigated the molecular architecture of the trunk nervous system in the annelid Platynereis dumerilii. Annelids belong to Bilateria, an evolutionary lineage of bilateral animals that also includes vertebrates and insects. Comparing nervous system development in annelids to that of other bilaterians could provide valuable information about the common ancestor of all Bilateria. We find that the Platynereis neuroectoderm is subdivided into longitudinal progenitor domains by partially overlapping expression regions of nk and pax genes. These domains match corresponding domains in the vertebrate neural tube and give rise to conserved neural cell types. As in vertebrates, neural patterning genes are sensitive to Bmp signaling. Our data indicate that this mediolateral architecture was present in the last common bilaterian ancestor and thus support a common origin of nervous system centralization in Bilateria.     

A new method for the quantification of superoxide dismutase mimics with an allopurinol–xanthine oxidase–lucigenin enhanced system

Allopurinol is a prodrug converted to oxypurinol by xanthine oxidase, a process followed by an efficient enzyme inhibition. Using a lucigenin-enhanced chemiluminescence method, we found that, under alkaline conditions, superoxide radicals are produced in large amounts in the first step of the interaction between the enzyme and the inhibitor. A comparison between lucigenin and cytochrome c as final detectors revealed that only the chemiluminescence technique is able to detect the superoxide anions from allopurinol oxidation. The allopurinol–xanthine oxidase–lucigenin system can be used for the quantification of various free-radical scavengers, in particular superoxide dismutase mimics. Three manganese compounds from different structural classes [manganese(II) chloride, manganese N,N′-bis(salicylidiene)ethylenediamine chloride, and manganese(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin] were compared at five concentrations (0.01, 0.1, 1, 10, and 100 μM). The method is fast, 16 times more sensitive than the cytochrome c assay at pH 10.1 and could be used for in vivo investigations avoiding the lucigenin redox cycle. If the concentrations of the reagents are increased and Tween 20 is added, the method is also operative at pH 7.4.     

In the family with ubiquitin

The Cold Spring Harbor meeting on 'The Ubiquitin Family', held in May 2011, brought together scientists from a wide range of fields under the umbrella of ubiquitin and ubiquitin-like protein structure, function and regulation.     

Cowhage-induced itch as an experimental model for pruritus. A comparative study with histamine-induced itch

Background

Histamine is the prototypical pruritogen used in experimental itch induction. However, in most chronic pruritic diseases, itch is not predominantly mediated by histamine. Cowhage-induced itch, on the other hand, seems more characteristic of itch occurring in chronic pruritic diseases.

Objectives

We tested the validity of cowhage as an itch-inducing agent by contrasting it with the classical itch inducer, histamine, in healthy subjects and atopic dermatitis (AD) patients. We also investigated whether there was a cumulative effect when both agents were combined.

Methods

Fifteen healthy individuals and fifteen AD patients were recruited. Experimental itch induction was performed in eczema-free areas on the volar aspects of the forearm, using different itch inducers: histamine, cowhage and their combination thereof. Itch intensity was assessed continuously for 5.5 minutes after stimulus application using a computer-assisted visual analogue scale (COVAS).

Results

In both healthy and AD subjects, the mean and peak intensity of itch were higher after the application of cowhage compared to histamine, and were higher after the combined application of cowhage and histamine, compared to histamine alone (p<0.0001 in all cases). Itch intensity ratings were not significantly different between healthy and AD subjects for the same itch inducer used; however AD subjects exhibited a prolonged itch response in comparison to healthy subjects ( p<0.001).

Conclusions

Cowhage induced a more intense itch sensation compared to histamine. Cowhage was the dominant factor in itch perception when both pathways were stimulated in the same time. Cowhage-induced itch is a suitable model for the study of itch in AD and other chronic pruritic diseases, and it can serve as a new model for testing antipruritic drugs in humans.     

Crosstalk between dihydroceramides produced by Porphyromonas gingivalis and host lysosomal cathepsin B in the promotion of osteoclastogenesis

Emerging studies indicate that intracellular eukaryotic ceramide species directly activate cathepsin B (CatB), a lysosomal‐cysteine‐protease, in the cytoplasm of osteoclast precursors (OCPs) leading to elevated RANKL‐mediated osteoclastogenesis and inflammatory osteolysis. However, the possible impact of CatB on osteoclastogenesis elevated by non‐eukaryotic ceramides is largely unknown. It was reported that a novel class of phosphoglycerol dihydroceramide (PGDHC), produced by the key periodontal pathogen Porphyromonas gingivalis upregulated RANKL‐mediated osteoclastogenesis in vitro and in vivo. Therefore, the aim of this study was to evaluate a crosstalk between host CatB and non‐eukaryotic PGDHC on the promotion of osteoclastogenesis. According to a pulldown assay, high affinity between PGDHC and CatB was observed in RANKL‐stimulated RAW264.7 cells in vitro. It was also demonstrated that PGDHC promotes enzymatic activity of recombinant CatB protein ex vivo and in RANKL‐stimulated osteoclast precursors in vitro. Furthermore, no or little effect of PGDHC on the RANKL‐primed osteoclastogenesis was observed in male and female CatB‐knock out mice compared with their wild type counterparts. Altogether, these findings demonstrate that bacterial dihydroceramides produced by P. gingivalis elevate RANKL‐primed osteoclastogenesis via direct activation of intracellular CatB in OCPs.